中南大学工业电炉英文课件.ppt

Chapter 1 Electric Resistance Furnace Chapter outline Introduction Direct heating resistance furnace Heating elements Radiative electric resistance furnace Convective electric resistance furnace Conductive electric resistance furnace Introduction Introduction Introduction Applications of electric resistance furnaces Electricity-heat conversion 3 Classification of electric resistance furnace 1) direct e.r.f 2) indirect e.r.f Applications of electric resistance furnaces Heating * Heat treatment * Smelting and melting Sintering Electricity-heat conversion Joule effect of electric current Joule-lenz law: (or Joule’s law) A physical law expressing the relationship between the heat generated by, and the current flowing in, a conductor. James Prescott Joule (1840s) and Heinrich Lenz Joule heating: The heating effect of conductors carrying currents is called Joule heating. Joule-lenz law Classification of electric resistance furnaces Direct resistance furnace Current passes through the material to be heated (object), which is electric resistance, and generates heat Indirect resistance furnace Heating elements Heat transfer process According to heat transfer mode , the indirect electric resistance furnace may be classified as : Radiative electric resistance furnace (radiation) Convective electric resistance furnace (convection) Conductive electric resistance furnace (conduction) * * For the Lab Removable bottom (车底式) Box-type (箱式) In metal processing industry: ( kcal or kJ ) : Current intensity, (A) : Resistance, (Ω) : Time of current conveyance, (s)